<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>Protein Phosphorylation Inhibition involves interference with, or restraint of, enzymatic activities involved in covalent transfer of a phosphate group from ATP to a protein via the action of a kinase. The major phosphoryl acceptors in proteins are serine, threonine, and tyrosine. Typically, such post-translational modifications regulate protein function.</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>